need rear disc brakes caliper bracket
 

Need to buy a set of rear disc brackets, dont want to buy a $600 complete set,,can put together all the parts i need,other than the bracket!

Depending on the type rear end.
You could try Ebay.

One of us "master truck builders" is going to have to get busy and fabricate this bracket. I can't find them for sale either (not by itself). They are always part of an expensive kit.